CONTROL AND INDICATING - DESCRIPTION AND OPERATION
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1. General
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The passenger oxygen control and indicating system controls the supply and operation of the passenger oxygen system. It also sends data to the cockpit systems about the condition of the passenger oxygen system.
2. Component Location__________________
(Ref. Fig. 001)
-------------------------------------------------------------------------------FIN | FUNCTIONAL DESIGNATION | PANEL|ZONE|ACCESS | ATA | | | | DOOR | REF. -------------------------------------------------------------------------------
16WR PRESS SW 211 35-23-15 910WR1 REGULATOR - OXYGEN 162 35-23-52 910WR2 REGULATOR - OXYGEN 162 35-23-52 960WR CONTROL UNIT-QUANT.CALCUL. 172 35-23-34 970WR SWITCH-LOW PRESSURE 172 35-23-54 975WR TRANSDUCER-TEMP. 172 35-23-11 980WR IND.-PRESS,FILL PANEL 172 35-23-21 990WR1 REDUCER - PRESSURE 172 35-23-51 990WR2 REDUCER - PRESSURE 172 35-23-51 990WR3 REDUCER - PRESSURE 172 35-23-51 990WR4 REDUCER - PRESSURE 172 35-23-51 990WR5 REDUCER - PRESSURE 172 35-23-51 990WR6 REDUCER - PRESSURE 172 35-23-51
7000WR VALVE- PRESS RELIEF 132 35-23-55
3. System Description__________________
The manually operated controls and the indications for the passenger oxygen system are installed on the panels 20VU, 21VU and 50VU. The altitude switch 16WR, which is installed in the avionics compartment, starts the automatic operation of the passenger oxygen system. It sends a signal to open the oxygen regulators 910WR1 and 910WR2, which supply low-pressure oxygen to the oxygen distribution system. If the altitude switch 16WR does not operate, you can use the 'MAN ON' pushbutton switch 14WR to start the manual operation. When the high pressure oxygen flows through the pressure reducers 990WR1 thru 990WR6, the oxygen pressure decreases to the pressure necessary to supply the oxygen regulators 910WR1 and 910WR2. There is one pressure reducer attached to each oxygen cylinder assembly. If there is an overpressure in the intermediate line the pressure relief valve 7000WR operates. This releases the unwanted oxygen overboard through the overboard discharge line.
Gaseous Oxygen System - Control and Indicating Figure 001 (SHEET 1)
EFF : 401-499, 35-23-00Page 2 Config-2 Aug 01/05
CES
Gaseous Oxygen System - Control and Indicating Figure 001 (SHEET 2)
EFF : 401-499, 35-23-00Page 3 Config-2 Aug 01/05
CES
The pressure reducers 990WR1 thru 990WR6 and the temperature transducer
975WR send signals to the Quantity Calculation and Control Unit (QCCU)
960WR. The QCCU 960WR sends a temperature adjusted signal to the POXIP,
which shows the crew the pressure in the oxygen cylinders.
The QCCU 960WR also sends a signal to the fill panel indicator 980WR. The
fill panel indicator 980WR shows how much pressure is in the oxygen
storage-cylinders without temperature adjustment.
The low-pressure switch 970WR sends a signal to the POXIP to tell the crew
when the system pressure is less than 5.5 +0.7 -0.7 bar (79.7707 +10.1526 -10.1526 psi). In this case, the REGUL LO PR message is shown on the POXIP.
If the system operated, you must push the 'TMR RESET' pushbutton switch 13WR
to set the system back to the normal condition.
4. Power Supply
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(Ref. Fig. 002)
The essential busbar 401PP supplies the oxygen control and indicating system
with 28VDC.
5. Component Description
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A. Altitude Switch 16WR
(Ref. Fig. 003) The altitude switch 16WR closes if the cabin pressure falls to a value equivalent to 14000 +0 -500 ft. (4300 +0 -150 m). This supplies a ground for the 'OPEN' relays 930WR and 931WR and the 'PASS INFO' relay 19WR. The oxygen regulators open when the 'OPEN' relays are energized.
B. 'MAN ON' Pushbutton Switch 14WR
(Ref. Fig. 003) The 'MAN ON' pushbutton switch 14WR lets the crew open the oxygen regulators 910WR1 and 910WR2 if the altitude switch 16WR does not operate. This supplies a ground for the 'OPEN' relays 930WR and 931WR the same as the altitude switch 16WR. The 'OPEN' relays have a self-holding circuit and stay open when you release the 'MAN ON' switch. The oxygen regulators open when you hold the 'MAN ON' pushbutton switch for 1 second. This is necessary if the 'OPEN' relays do not operate. The 'MAN ON' pushbutton switch has a safety guard, which prevents accidental operation of the system.
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